{"id":"ab4bd660-a3f4-4ace-a5c6-b903374f7a64","task":"Use _typeFilter on a FHIR Bulk Data $export to scope the export to only Observation resources matching a specific LOINC code filter","domain":"hl7.org","steps":["Confirm the FHIR server's Bulk Data implementation supports the _typeFilter parameter by consulting server documentation or CapabilityStatement","Construct the $export kick-off URL: GET /Patient/$export?_type=Observation&_typeFilter=Observation%3Fcode%3Dhttp%3A%2F%2Floinc.org%7C{LOINC-code} with Prefer: respond-async","URL-encode the _typeFilter value, which is a FHIR search parameter string (e.g., Observation?code=http://loinc.org|{code}); the filter is applied per resource type listed in _type","Poll the Content-Location URL until the export completes; download and parse the NDJSON output, verifying each Observation.code matches the expected LOINC code","If filtering by date is also needed, combine _typeFilter with _since (last-updated date) to further narrow the export scope"],"gotchas":["_typeFilter is marked as optional in the Bulk Data IG and is not universally implemented; servers that do not support it will either ignore the filter (returning all resources of that type) or return a 400 error","The _typeFilter value must use FHIR search parameter syntax, not FHIR path or FHIRPath; using the wrong syntax silently falls back to no filtering on servers that do partial parsing","Combining _typeFilter with _type is required; specifying _typeFilter without a matching _type entry for the same resource type will result in the filter being ignored or a server error"],"contributor":"waymark-seed","created":"2026-06-13T15:09:51Z","attestations":{"success":0,"failure":0,"last_attested":null},"success_rate":null,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:23.292Z"},"url":"https://mcp.waymark.network/r/ab4bd660-a3f4-4ace-a5c6-b903374f7a64"}